This application claims the benefit of Korean Application No. 99-45851, filed Oct. 21, 1999, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a micro actuator for supporting and finely moving a head device for recording or reproducing information on or from a recording medium.
2. Description of the Related Art
In general, a disk drive such as a hard disk drive (HDD) includes a head suspension assembly for supporting a head for recording or reproducing information on or from a track of a disk rotatably installed in a housing.
The head suspension assembly includes a rod beam, that is, a suspension, supported at an end portion of an actuator arm pivoted by a voice coil motor (VCM), a gimbal connected to an end portion of the suspension, and a slider supported at the gimbal and having the head. The suspension pivots together with the actuator arm by a driving force of the voice coil motor. While pivoting the suspension transfers the slider to a predetermined position across a disk. Here, the head supported by and transferred together with the slider must be positioned at a predetermined track, where information to be recorded or reproduced is located, among a plurality of tracks provided at the disk. The tracing of a track by the head is very important for reliability of recorded or reproduced information.
Due to a recent trend in which the storage capacity of compact disc drives is increasing, the track density (track per inch; TPI) of the disk has also increased. However, as TPI and the rotation speed of the disk increase, controlling the position of the head precisely becomes more difficult. To solve this difficulty, a head suspension assembly having an additional precise tracking motor or a micro actuator has been suggested.
FIG. 1 shows a head suspension assembly disclosed in U.S. Pat. No. 5,857,347. The head suspension assembly, as shown in the drawing, includes a rod beam 10 connected to an end portion of an actuator arm (not shown), a Gimbal 17 connected to an end portion of the rod beam 10, a micro actuator 20, and a connection portion 30.
The rod beam 10 has a horizontal portion 15 formed between an end portion 11 and a central end portion 13. The Gimbal. 17 supports a slider (not shown) having a head for recording/reproducing (not shown). The micro actuator 20 has a first coil unit 21 and a second coil unit 23 which are installed consecutively above the upper surface of the rod beam 10. The connection portion 30 elastically connects the end portion 11 and the central end portion 13.
In the above structure, when current is applied to coils 22 and 24 of the first and second coil units 21 and 23, a vertical repulsive force is generated by an electromagnetic force between the respective coil units 21 and 23. Then, as each of the coil units 21 and 23 is moved up and down by the vertical repulsive force, vertical rail portions 31 and 33 of the connection portion 30 receive a force in a horizontal direction. As a result, as the end portion 11 pivots in a horizontal direction with respect to the central end portion 13, that is, in a track direction, the head is finely adjusted together with the slider.
However, in the above conventional micro actuator, many parts are required and the structure is complicated. Thus, practical application is difficult and production is expensive. Also, a great driving force is required to drive the rod beam including the slider, thus, much power is lost in a process for converting the vertical repulsive force generated between the coil units to a force in the horizontal direction.
To solve the above problems, it is an object of the present invention to provide a micro actuator having an improved structure by which the structure is simplified and a great force can be obtained with low electric power. Additional objects and advantages of the invention will be set forth in part in the description which follows, and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve the above and other objects, there is provided a micro actuator comprising a slider supported by an actuator arm which pivots in a track direction across a track of a recording medium, the slide adapted to slide above the recording medium and having an accommodating portion facing the recording medium, a first magnetic core arranged to move in the accommodating portion, for supporting a head device. A second magnetic core is separated a predetermined distance from and facing the first magnetic core and installed in the accommodating portion such that the center of the first magnetic core in a magnetic direction, which is perpendicular to the track direction and horizontal with respect to the surface of the recording medium, is offset from the center of the first magnetic core. A first magnetic coil is wound around the first magnetic core so that the axis of the first magnetic coil runs in the vertical direction and a magnetic force in a direction perpendicular to a surface of the recording medium is generated when current is applied. A leaf spring elastically connects the first magnetic core and the inner side of the accommodating portion in the track direction. When current is applied to the first magnetic coil, the first magnetic core is moved in the track direction by a magnetic force generated between the magnetic cores.
It is preferred in the present invention that the micro actuator further comprises a second magnetic coil wound around the second magnetic core so that, when current is applied, a magnetic force in the magnetic direction is generated.
Also, it is preferred in the present invention that the leaf spring and the slider are integrally formed of a silicon material.
Also, it is preferred in the present invention that the leaf spring comprises a first flat portion parallel to the track direction, and a second flat portion perpendicularly extended from the first flat portion to be parallel to the magnetic direction, in which the respective flat portions are continuously and alternately formed in the track direction.
Also, it is preferred in the present invention that the leaf spring is formed to be continuously and alternately bent in the track direction to have a greater rigidity coefficient value in the magnetic direction than that in the track direction.
Also, it is preferred in the present invention that the first magnetic core comprises a plate type first magnetic portion in which one side thereof can be arranged to be perpendicular to the vertical direction, and a second magnetic portion perpendicularly extended and bent from the first magnetic portion so that one side of the second magnetic portion is perpendicular to the track direction, in which the first and second magnetic portions are continuously and alternately formed in the track direction.
Also, it is preferred in the present invention that the first magnetic coil is repeatedly interwoven back and forth in the track direction around the second magnetic portions and wound around the outside of the second magnetic portion.
According to another aspect of the present invention, there is provided a micro actuator comprising a slider supported by an actuator arm which pivots in a track direction across a track of a recording medium, the slider adapted to slide above the recording medium and having an accommodating portion facing the recording medium. A first magnetic core is arranged to move in the accommodating portion, for supporting a head device. A pair of second magnetic cores is separated a predetermined distance from and facing the first magnetic core with respect to a magnetic direction, which is perpendicular to the track direction and horizontal with respect to the surface of the recording medium, and installed in the accommodating portion such that the respective centers thereof with respect to the magnetic direction are disposed at both sides of the center of the first magnetic core. A first magnetic coil is wound around the first magnetic core with respect to the vertical direction so that a magnetic force in a direction perpendicular to the surface of the recording medium is generated when current is applied. Second magnetic coils are wound around each of the second magnetic cores with respect to the vertical direction so that a magnetic force is generated in the vertical direction when current is applied. A leaf spring elastically connects the first magnetic core and the inner side of the accommodating portion in the track direction. By applying current to the first magnetic coil and selectively applying current to each of the second magnetic coils, the first magnetic core is moved back and forth in the track direction by an electromagnetic force generated between the magnetic cores.
Also, it is preferred in the present invention that the leaf spring is formed to be continuously and alternately bent in the track direction to have a greater rigidity coefficient value than that in the magnetic direction.